Recovery and purification of molybdenum from Ni–Mo ore by direct air oxidation in alkaline solution

A direct hydrometallurgical process for molybdenum extraction and recovery from a Ni–Mo ore is reported. The novel technology includes leaching molybdenum by air oxidation in alkaline solution，purifying the leach solution with freshly precipitated “nascent” Fe(OH)3 and “buffer agent” NaHCO3, enriching molybdenum by ion exchange and crystallizing ammonium molybdate tetrahydrate. Compared with the traditional roasting methods for such ores, this new technology avoids SO2 and As2O3 pollution problems. More than 98% Mo was leached in the process and through selective adsorption, about 95% W could be removed from the molybdenum leach solution under the optimized conditions. The Mo/W separation factor was up to 100. Impurities of V, As and P were simultaneously removed, along with W, with efficiencies reaching 95.5%, 99.7% and 57.1%, respectively. The final product of ammonium molybdate tetrahydrate was in accord with the standard specification (GB/T 3460–1982).